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  1. #1
    Join Date
    Aug 2002
    Location
    San Diego, CA
    Posts
    476

    Default Need help with a mystery Battery Drain!

    Hey Guys,
    Can anyone steer me in the right direction here? I picked up a '69 LeMans (sorry, it has a dawg pie Chivvy 350, no less), and it seems to have a drain on the battery.
    I don't have a multimeter, but I do have a basic 6-12v test light. When I touch the fuses for Radio, Tail, Wiper & Stop with the ignition switch in the "Off" position, my tester lights up. Do those circuits normally have current going through them when the ignition is off? There had been an aftermarket detachable face stereo, which just has the base with no head unit. The wires for it are capped off under the dash.
    When the guy put the SBC in it he apparently left off the factory braided ground strap to the firewall. Would that cause this type of drain? Other than that I can't see any obvious loose or unconnected wires or unconnected grounds anywhere on the car.
    What should be my next step in tracking it down? Thanks in advance for any help!
    Current Buick: 1973 Apollo Coupe 350/350
    Previous Buicks:
    1972 Skylark 2-door HT 350/350
    1969 Electra 4-door HT 430/400
    1969 Skylark 2-door HT 350/350
    1973 Apollos (3)--all 350/350)
    1971 Skylark 2-door HT 350/350
    1970 LeSabre 4-door HT 350/350

    --Chris

  2. #2
    Join Date
    Jul 2007
    Posts
    222

    Default Re: Need help with a mystery Battery Drain!

    I posted this in March, hope it is helpful for you to find your problem.

    Connect a small bulb in series between the negative terminal post on the battery and the negative cable. If the light lights bright there is a heavy current flow, if dim a light a little flow. If no light there is no flow. To make sure the connection is good turn on the headlights and the bulb should light. Turn lights off and ignition on and see what the difference is. Turn ignition off again. If the light is on at all pull fuses until it goes out and you will have found the source of current flow causing the battery to discharge. On the older cars the clocks were generally a source of dead batteries because they used a magnetic coil to wind the works. If the contacts burned closed it would discharge the battery but not blow the clock fuse. Good luck.

  3. #3
    Join Date
    Dec 2009
    Location
    Brew City Wisconsin
    Posts
    3,343

    Default Re: Need help with a mystery Battery Drain!

    If you havent already, I would start with the age, condition, and connection at the battery itself.
    William
    1966 Wildcat


    IF ITS GOOD, IT AINT CHEAP. AND IF ITS CHEAP, IT AINT GOOD!

  4. #4
    Join Date
    Aug 2002
    Location
    San Diego, CA
    Posts
    476

    Default Re: Need help with a mystery Battery Drain!

    Thanks for the responses so far.
    The battery, alternator and voltage regulator are all brand new.
    Tom, if I'm not mistaken, that technique you mentioned with the bulb lighting up is basically the same thing that my tester is accomplishing.
    I can tell that there IS a drain, and that current is flowing where it shouldn't with the ignition off. What I need to know is how to make it stop.
    Thanks again for the help, guys.
    Current Buick: 1973 Apollo Coupe 350/350
    Previous Buicks:
    1972 Skylark 2-door HT 350/350
    1969 Electra 4-door HT 430/400
    1969 Skylark 2-door HT 350/350
    1973 Apollos (3)--all 350/350)
    1971 Skylark 2-door HT 350/350
    1970 LeSabre 4-door HT 350/350

    --Chris

  5. #5
    Join Date
    Feb 2002
    Location
    Sacramento CA area
    Posts
    3,195

    Default Re: Need help with a mystery Battery Drain!

    You need to connect an ammeter in series with current flow; read the current; start pulling fuses, see what results in a drop.
    BadBrad
    '70 GS455 - Power Brute Super T10 4spd
    ex. '70 GSX
    New Project: 2000 Mercury Grand Marquis - for the kids to drive.
    New Muscle: 2013 Ford Taurus SHO - Twin Turbo Terror

    Spare 455 on the stand, just in case!


    Slideshow of BadBrad's Car: http://s517.photobucket.com/albums/u...view=slideshow

  6. #6
    Join Date
    Feb 2002
    Location
    NY
    Posts
    13,472

    Default Re: Need help with a mystery Battery Drain!

    tail and stop are not switched through the ignition circuit - radio and wiper are.
    Alan W

    BPG # 1048 - Charter Member
    NE GS/GN Club - 17 Year Member
    68/69 Buick StepChild Nation - 29 Year Member

    What is a Buick StepChild ?
    Quote Originally Posted by 442w30 View Post
    ... They have awkward proportions from certain angles, and they look dumpy compared to their GM brethren
    ....'68 SportWagon400 "Sportn'Wood"..............'69 GS400 Convert "BigRed"..........

  7. #7
    Join Date
    Jul 2007
    Posts
    222

    Default Re: Need help with a mystery Battery Drain!

    You are correct that the bulb is going to do the same as the meter, however it is easier to see it while working around the fuses etc. than looking at the meter. It is an old method but works really well.

  8. #8
    Join Date
    Jun 2005
    Location
    berkley, mass.
    Posts
    2,927

    Default Re: Need help with a mystery Battery Drain!

    if you can get a multi meter then that would be better. on an older car no more than 10 milli amps with the radio hooked up. sounds like you have a major draw which a test light or a regular bulb wired in series between the negative battery cable and terminal will work. if you pull all of the fuses and it is still on try unplugging the alternator. by the way you mis spelled your town .
    paul c.
    65 skylark conv. 455/th400
    79 z28 w/a dart block and headed 555 bbc. hopefully 9.50
    2 jetskis
    mountain bikes and road bikes
    no more hobbies please

  9. #9
    Join Date
    Feb 2002
    Location
    Upstate NY 13901
    Posts
    5,820

    Default Re: Need help with a mystery Battery Drain!

    On a separate note....you mentioned no ground strap. Having proper grounds is vital to the electrical system 'playing nice'.

    Picture a triangle of the body/frame, engine, and battery. Each should be grounded to the other two. Don't overlook nice clean connections & dielectric grease too.

    That was one of the first lessons I learned on my first car. I had an Olds Omega with an Olds 455. Pulled into my friend's dad's welding shop. Went to leave and it cranked over real slow. He came out and pulled off the top mount battery terminals. He pointed to the grey and black junk on the terminals and battery posts and said, "these ALWAYS need to be shiny clean".

    He cleaned them both up, put the terminals back on and it fired right up.

    I guess that's enough of a tangent.
    Scott B.


    72 GS 455 Stage 1, 70 Skylark, 92 Roadmaster

    Acts 4:12 - Salvation is found in no one else, for there is no other name under heaven given to men by which we must be saved.

  10. #10
    Join Date
    Dec 2009
    Posts
    101

    Default Re: Need help with a mystery Battery Drain!

    10 years ago when I finished restoring my '65 hardtop I had a battery drain that was very hard to find. Every time I pulled the battery cable and checked for a drain, it came up with no problem. Then, 2 days later, I'd have a dead battery. Here's what I learned. first when dealing with a freshly restored car you do need to check all your grounds. Often fresh paint will keep your grounds from making contact. Also when the car has vibrated many extra grounds over 100,000 miles of travel, it sometimes makes original grounds, like the engine ground strap, ancillary.

    My problem was caused by the voltage regulator sticking. Evidently it never stuck when I checked for voltage drain, but then would and drain the battery. Just like leaving the key on.

    Rufus
    I don't wreck 'em, I just keep saving 'em!

  11. #11
    Join Date
    Aug 2002
    Location
    San Diego, CA
    Posts
    476

    Default Re: Help with a mystery Battery Drain!*(UPDATE)*

    Thanks a lot guys, for all the nice responses. I really appreciate the teamwork on this board.
    Well, I THINK I found what the problem is...
    When I was turning off the ignition it was going past the "OFF" position into the "AUX" position below it--apparently the lock cylinder is worn too much. The key can also be pulled out of the ignition with it still in the "ON" position--I guess that happens quite a bit on cars with a 40+ year-old ignition cylinder.
    Anyway, when I put the ignition into the proper "OFF" position, those fuse circuits in the block no longer light up my tester, and the "GEN" idiot light on the dash no longer is glowing like before.
    So, I think that might be it, but I'll try leaving the battery hooked up over night and if it's still got juice tomorrow morning. If it does, I think we'll say maybe I dodged a bullet this time. I still need a ground strap though.
    As a side note, anybody know why exactly the factory firewall ground straps always seem to be un-insulated, braided straps, as opposed to just regular insulated wire? The battery neg. cable ground on the front of the chassis is insulated wire--just wondering...
    Thanks again, guys for the input.
    Current Buick: 1973 Apollo Coupe 350/350
    Previous Buicks:
    1972 Skylark 2-door HT 350/350
    1969 Electra 4-door HT 430/400
    1969 Skylark 2-door HT 350/350
    1973 Apollos (3)--all 350/350)
    1971 Skylark 2-door HT 350/350
    1970 LeSabre 4-door HT 350/350

    --Chris

  12. #12
    Join Date
    Jul 2007
    Posts
    222

    Default Re: Need help with a mystery Battery Drain!

    There is no need to insulate the ground strap since it goes from ground potential to ground poential and there is nothing carrying power in the area of it. Around the battery there is a chance of creating a short circuit with the power leads coming from the battery.

  13. #13
    Join Date
    May 2009
    Location
    La Quinta, CA (Palm Springs)
    Posts
    438

    Default Re: Need help with a mystery Battery Drain!

    Had the same problem a few months back. Found out the aftermarket radio was wired wrong (would play with ignition off), and it slowly drained the battery. I guess it was "hot wired".
    Mike

  14. #14
    Join Date
    Feb 2002
    Location
    NY
    Posts
    13,472

    Default Re: Help with a mystery Battery Drain!*(UPDATE)*

    Quote Originally Posted by smokum View Post

    I still need a ground strap though.
    Yes you do, and alot sooner than later.

    I was told of a story where a guys GS burned to the (cough) ground because he didn't have a ground strap from the firewall to the engine ... the system ended up grounding itself through the trans to the shifter cable and up into the carpet
    Alan W

    BPG # 1048 - Charter Member
    NE GS/GN Club - 17 Year Member
    68/69 Buick StepChild Nation - 29 Year Member

    What is a Buick StepChild ?
    Quote Originally Posted by 442w30 View Post
    ... They have awkward proportions from certain angles, and they look dumpy compared to their GM brethren
    ....'68 SportWagon400 "Sportn'Wood"..............'69 GS400 Convert "BigRed"..........

 

 

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